1. Field of the Invention
The present invention relates to door assemblies and, more particularly, to door thresholds and sealing members therefor.
2. History of the Prior Art
The use of thresholds in residential and commercial buildings is an integral part of conventional construction. External doors are most effectively mounted in conjunction with a lower plate or threshold member above which the door may be oriented in the closed position. The threshold serves multiple functions. It reduces the distance between the surface above which the door swings and the bottom of the closed door and it functions as a barrier to air and moisture infiltration. In some designs, sealing members are incorporated with the door to further reduce, or substantially eliminate, moisture infiltration under the closed door.
Prior art thresholds have incorporated a variety of designs. Common styles include elongate and tapered configurations in a variety of shapes and sizes adapted for positioning beneath the swinging door. In the main, the thresholds include a first portion adapted for facing the interior of the building as defined by the threshold and door assembly. A second portion faces outwardly from the building. The outwardly facing portion is generally designed to repel water and inhibit the infiltration of air therebeneath. The threshold is thus conventionally made of wood or metal and assembled to withstand inclement weather without readily deteriorating. Metal thresholds are generally best suited for resisting prolonged moisture without structural degradation. Usually, the metal thresholds are formed with a hollow space therebeneath to reduce cost and weight to maximize design effectiveness. Design parameters for the threshold also include its length, width, cross-sectional shape, manner of securement to the underlying floor, and manner of sealing engagement with the door disposed thereabove.
Present day threshold sealing systems have advanced in design to improve the efficiency of sealing and door operation. The systems often include gaskets and flanges which may be secured to the bottom of the door. Many of these sealing members effectively prevent infiltration of moisture except when the door is moving to a closure position. Unfortunately, in certain instances the sealing member can actually sweep moisture off of the threshold into the building area. The intent of the sealing members is, of course, to resist the intrusion of water as well as wind loading, driving rain, and thermal degradation.
Several U.S. Patents have addressed these issues. For example, U.S. Pat. No. 4,413,446 illustrates a threshold assembly for mounting on a door and door sill utilizing a flexible magnet holding device for enhanced reliability against water infiltration. The magnets described therein are constructed so that the opposed edges have opposite polarity. Such sealing weather stripping closures have been the subject of other design efforts. For example, U.S. Pat. No. 4,411,104 teaches a door bottom and sill assembly. The sill portion of this particular structure mates with a sealing member when the door is in a closed position forming a weather barrier. Likewise, U.S. Pat. No. 2,739,357 teaches a combined weather stop and scuff plate for closure devices. In this particular design the threshold is constructed to engage a sealing member projecting downwardly from the door in a configuration enhancing the sealing thereof. Similarly, U.S. Pat. No. 2,319,709 teaches a sealing strip for use with moveable closures such as doors or windows to seal the clearance spaces around such structures. In these prior art references, the sealing lips are often angulated with the sealing members forming rather large sealing surfaces with the jamb region extending outwardly from beneath the door. Such structures can, however, create water infiltration problems because water can accumulate in areas prone to the movement of water into the structure.
It would be an advantage to overcome the problems of prior art systems by providing a threshold assembly capable of providing an improved system for preventing moisture and air infiltration while overcoming the disadvantages of the prior art. The present invention provides such a system by incorporating a threshold containing a sealing lip adapted for engaging a sealing member secured to the door and an outer recessed threshold region for substantially reducing the amount of water that could be swept in by the door.